The invention pertains to a flange connection in a design as a pipe connection device with a screw-on flange part, set on the outside of the pipe to be connected to by means of at least two screws with a counter piece, whereas a sleeve formed insert piece adapted to the contour of the connecting pipe with widened end can be inserted into the pipe provided with the widened end, said insert piece forming the pipe connection on its outer face and whereupon the screw-on flange part overlaps an additional clamping ring, with its inside contour matching the contour of the widening of the pipe end, slid on the outside of the widened pipe end.
A flange connection featuring screw couplings is known, for example, from the ISO-norm 6162 or 6164. Such flange connections are suitable and designated for the connection of two pipes together as well as for the connection of a pipe end with a connecting block, for example with a valve block. In the case of the known flange connections, standard ISO flange parts sit in each case on a formed pipe end fitting with a stepped outside contour corresponding to the ISO flange part, which is joined with the pipe to be connected by means of pipe-to-pipe weld joint. Herewith there is the disadvantage that the fabrication of the pipe end pieces, as well as their welding on the pipe to be connected, is laborious, whereas the necessary weld joint displays a certain weak spot in the case of later application of the pipe-flange-connection.
A flange connection of another design with a flange piece different from the ISO standards is described in the GB PS 1 232 938. In the case of the known pipe connection, the end of the pipe to be connected has a conically formed widening into which an insert piece featuring a conical outer surface is pushed. The insert piece has a sleeve form constructed with a central opening corresponding to the pipe cross section of the cylindrical pipe body, so that a flow passage from the cylindrical pipe body through the insert piece is provided. The outer face surface of the insert piece is either attached against a connecting block or against the outer face surface of an insert piece pushed into the pipe end of a second pipe, so that two pipe ends can be connected together by means of appropriately assigned insert pieces. Corresponding conical formed clamp pieces, which are overlapped by a flange piece, are arranged on the outside of the pipe end with the widened form. This flange piece is screwable by means of corresponding screw connections either with the connecting block or with a flange piece arranged on a second pipe end, so that the pipe connection is producible by means of the tightening of the corresponding screws. The flange piece has a conical form on its inner surface surrounding the clamp piece corresponding to the conical form of the clamp piece.
Associated with this pipe connection device is firstly the disadvantage that the transition of the conical widening in the cylindrical pipe body has a kinking point which, in the case of high vibration stress of the connected pipe or the pipes connected to each other, can result in a corresponding sensitivity to breakage. Furthermore there has been the result with the known pipe connection devices, especially in the case of large pipe diameters and high pressures, that the conical widening of the pipe body thereto tends to evade the cylindrical pipe form and thereby to slip out of the pipe connecting device.
A pipe connection of another design is known from GB 740 717, by which the connection of the pipe ends takes place by means of a screw nut threaded connection system. Here, in each case, clamp rings are attached to the outside of the pipe ends which have a widening end, said clamp rings having a support bearing or alternatively a male screw thread for a sleeve formed coupling nut such that the coupling nut grasping the clamp ring of one pipe end is screwed onto the clamp ring with male thread on the other pipe end and thereby pulls the clamp rings and hence the pipe ends together. Here the adapter pieces inserted into the widened pipe ends are also known. Associated with this pipe connection is the disadvantage that—as apposed to the known flange connection named at the beginning—a torsion movement is transferred to the widened area at the end of the pipes during the assembly of the screw nut coupling system, such that the pipes to be connected possibly rotate at the same time. This effect is, as a rule, undesirable in the case of the adjustment of pipes to be connected together.